Air filter for filtering induced air for internal combustion engines of motor vehicles

ABSTRACT

In an air filter for filtering the intake air for internal combustion engines of motor vehicles, with a filter housing, which has an air inlet, an air outlet, and at least one water outlet disposed in the housing bottom, and with a replaceable filter matte disposed in the filter housing between the air intake and air outlet, in order to separate water particles from the intake air and in order to optimally discharge the separated water from the filter housing, a water separator is disposed upstream of the filter matte in the filter housing and means are provided in the at least one water outlet, which produce a water level in the water outlet of such a height that the vacuum in the filter housing acting on the water outlet is compensated for.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a 35 USC 371 application of PCT/DE 00/03043 filed onSep. 5, 2000.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an air filter and particularly to such a filterfor filtering the intake air for internal combustion engines of motorvehicles.

2. Description of the Prior Art

Air filters for filtering the intake air for internal combustion engineswhich are known for example from Bosch “KraftfahrtechnischesTaschenbuch” [Automotive Handbook] 1998, p. 422 ff., to keep the dustcontained in the intake air away from the engine and prevent a prematurewear on the engine. The filter matte, which retains the dust and must bereplaced at maintenance intervals, is matched to the engine in order tooptimize performance, fuel consumption, and damping of the intake noise.A number of outlet bores are provided in the bottom of the filterhousing in order to discharge condensation water that forms in thefilter housing.

U.S. Pat. No. 5,507,858 has disclosed a device for separating thegaseous and fluid liquid phases of a gas/oil mixture in a pipeline,which has a housing with an inlet and an outlet inserted into thepipeline, which housing contains a water separator. The water separator,which is comprised of a perforated plate, is aligned in oblique fashion,i.e. at an acute angle to the axes of the inlet and outlet, and dividesthe housing into a housing section connected to the inlet and a housingsection connected to the outlet. A liquid outlet is provided in thelatter housing section so that the liquid being separated in the waterseparator can be discharged from the housing.

SUMMARY OF THE INVENTION

The air filter according to the invention, has the advantage that on theone hand, water particles contained in the intake air are precipitatedin the water separator and adhere to the bottom of the filter housingand on the other hand, the water collecting at the bottom of the filterhousing is also reliably discharged via the water outlet duringoperation of the engine and does not collect in the dead flow spaces ofthe filter housing. As a result, the filter matte in the filter housingbecomes less moist and cannot become fully laden with moisture so thatsecondary malfunctions on the clean air side due to water passingthrough the fully laden filter matte can be prevented.

According to an advantageous embodiment of the invention, the necessarywater level in the water outlet is realized by virtue of the fact thatan outlet opening in the filter housing is connected to an outlet tubein the course of which an annular loop or a meandering bow is embodiedafter the fashion of a water seal. In this connection, the outlet tubeis preferably embodied as a hose.

According to a preferred embodiment of the invention, the means forproducing the water level have an outlet tube which leads from an outletopening in the filter housing and is filled with absorbent material. Asimilar absorption effect is also produced by means of a high surfaceroughness of the inner tube wall of the outlet tube or through theprovision of a constriction in the course of the outlet tube.

All the above-mentioned embodiments have the advantage that less spaceis required underneath the filter housing to accommodate the outlet tubethan is the case with the embodiment of a loop or bow in the outlettube. In addition, there is not a constant water seal in the outlet tubewhich can freeze in winter, but instead, the water level is only builtup to the required level during operation of the engine through themechanism of absorbency. Trials have shown that an improved waterseparation is produced, independent of this fact.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained in detail in the description below inconjunction with exemplary embodiments shown in the drawings, in which;

FIG. 1 is a longitudinal section through an air filter for the intakesection of an internal combustion engine,

FIG. 2 shows a detail of a side view of the lower region of the airfilter in FIG. 1 according to a second exemplary embodiment, and

FIGS. 3-5 each show a longitudinal section through the lower region ofthe air filter in FIG. 1 according to additional exemplary embodiments.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 schematically depicts a longitudinal section through an airfilter for filtering the intake air of an internal combustion engine ina motor vehicle, which has a filter housing 10 with an air inlet 11, anair outlet 12, and a replaceable filter matte 13 dispose between the airinlet 11 and air outlet 12. The air inlet 11 is provided with an airinlet fitting 14 and the air outlet 12 is provided with a connectionfitting 15 which, after installation of the filter housing 10 in themotor vehicle, is connected to the intake tube of the internalcombustion engine. In the installation position, the filter matte 13 isaligned for example horizontally and divides the inner chamber of thefilter housing 10 into a lower housing chamber 16 whose upper regioncontains the air inlet 11 and an upper housing chamber 17 which isconnected to the air outlet 12. The housing bottom 101 of the filterhousing 10 is embodied in the shape of a funnel and at its deepestpoint, is provided with a water outlet 18.

In order to improve water separation from the air, which enters via theair inlet 11 and is laden with moisture or water droplets, a waterseparator 19 is disposed upstream of the filter matte 13. The waterseparator 19 is inclined at an acute angle to the axis of the air inlet11 and separates the lower housing chamber 16 from a frontal region 20which contains both the air inlet 11 and the water outlet 18. The waterseparator 19 is embodied as a grating, e.g. made of non-rusting, knittedmetal, or the like wherein the grating meshes or honeycombs are, forexample, approximately 0.8×1.6 mm in size. During driving operation, avacuum prevails in the filter housing 10, which cannot discharge thewater, which has been precipitated from the air flow and has collectedat the housing bottom 101, via the water outlet 18, or can only do sopoorly. As a result, the filter matte 13 can become fully laden withwater and, after its storage capacity is expended, water penetratesthrough the filter matte 13, gets into the clean air-side intake sectionof the engine, and can cause malfunctions in sensors disposed there. Inorder to prevent this, means are disposed in the water outlet 18, whichproduce a water level in the water outlet 18 of such a height that thevacuum acting on the water outlet 18 is compensated for. These means canbe realized in various ways, where in all cases, the water outlet 18 isprovided with an outlet tube 21 which leads on the underside of thefilter housing 10 and encompasses an outlet opening 22 in the housingbottom 101.

In the air filter shown in FIG. 1, the means for producing the waterlevel are realized by means of a loop 24 embodied in the course of theoutlet tube 21, which is preferably embodied as a hose. A water column23 (indicated by hatching in FIG. 2) is always present in this loop 24and, with a corresponding embodiment of the loop 24, neutralizes theaction of the vacuum prevailing in the filter housing 10 on the wateroutlet 18. Instead of the loop 24, the outlet tube 21 can also beembodied with a meandering bow 25 (FIG. 2) by virtue of the outlet tube21 being provided with two 180° bends. The height of the bow 25determines the height of the water column 23 always present in theoutlet tube 21, in order to compensate for the vacuum in the filterhousing 10.

In the exemplary embodiment of FIG. 3, in a tube section remote from theoutlet opening 22, the outlet tube 21 is provided with a constriction 26of its internal diameter. Due to the constriction 26, the water level inthe outlet tube 21 required for the compensation of the vacuum in thefilter housing 10 automatically builds up only in the course of drivingoperation. When the engine is switched off and therefore when the vacuumis in the process of ceasing, the water is discharged completely fromthe filter housing 10 so that in winter, the water outlet 18 isprevented from freezing.

The same effect of the water level, which automatically builds up as aresult of increasing water entry into the air filter during drivingoperation, is achieved with the embodiment of the outlet tube 21according to FIG. 4. In this instance, the inner tube wall of the outlettube 21 is provided with a considerable surface roughness 27.

With the means for producing the water level shown in FIG. 5, themechanism of absorbency is used to produce the required water levelduring driving operation. In this instance, the means are realizedthrough an absorbent material 28 with which the intake tube 21 isfilled. An absorbent material of this kind can be a sponge or a textilewick.

In all of the exemplary embodiments according to FIGS. 2 to 5, theoutlet tube 21 can be embodied as a hose.

The foregoing relates to preferred exemplary embodiments of theinvention, it being understood that other variants and embodimentsthereof are possible within the spirit and scope of the invention, thelatter being defined by the appended claims.

We claim:
 1. In an air filter for filtering the intake air for internalcombustion engines of motor vehicles, with a filter housing (10), whichhas an air inlet (11) connected to an intake fitting (14) and an airoutlet (12) that can be connected to an intake tube of the engine, andat least one water outlet (18) disposed in the housing bottom (101), andwith a replaceable filter matte (13) disposed in the filter housing (10)between the air intake (11) and air outlet (12), the improvement whereina water separator (19) is disposed upstream of the filter matte (13) inthe filter housing (10) and means are provided in the at least one wateroutlet (18), which produce a water level (23) in the water outlet (18)of such a height that the vacuum in the filter housing (10) acting onthe water outlet (18) is compensated for.
 2. The air filter according toclaim 1, wherein the means for producing the water level have an outlettube (21) which leads from an outlet opening (22) in the filter housing(10) and has a loop (24) or a meandering bow (25) embodied in it.
 3. Theair filter according to claim 1, wherein the means for producing thewater level have an outlet tube (21) which leads from an outlet opening(22) in the filter housing (10) and, in a tube section remote from theoutlet opening (22), is provided with a constriction (26) of itsinternal diameter, the constriction being sized and configured so thatwater will build up while the engine is operating, and be released whenthe engine is shut down.
 4. The air filter according to claim 1, whereinthe means for producing the water level have an outlet tube (21) whichleads from an outlet opening (22) in the filter housing (10) and has ahigh surface roughness (27) on the inside for controlling the amount offluid which flows through the tube.
 5. The air filter according to claim1, wherein the means for producing the water level have an outlet tube(21) which leads from an outlet opening (22) in the filter housing (10)and whose hollow inside is filled with an absorbent material (28). 6.The air filter according to claim 5, wherein a sponge or a textile wickis used as the absorbent material.
 7. The air filter according to claim2, wherein the outlet tube (21) is embodied as a hose.
 8. The air filteraccording to claim 1, wherein the water separator (19) is disposedinclined at an acute angle to the axis of the air inlet (11) of thefilter housing (10) and separates the lower inner chamber (16) of thefilter housing (10) disposed beneath the filter matte (13) from afrontal region (20) which contains the air inlet (11) and the wateroutlet (18).
 9. The air filter according to claim 1, wherein the waterseparator (19) is embodied as a grating.
 10. The air filter according toclaim 9, wherein the grating meshes or honeycombs are approximately0.8×1.6 mm in size.
 11. The air filter according to claim 3, wherein theoutlet tube (21) is embodied as a hose.
 12. The air filter according toclaim 4, wherein the outlet tube (21) is embodied as a hose.
 13. The airfilter according to claim 8, wherein the outlet tube (21) is embodied asa hose.
 14. The air filter according to claim 6, wherein the outlet tube(21) is embodied as a hose.
 15. The air filter according to claim 2,wherein the water separator (19), is disposed inclined at an acute angleto the axis of the air inlet (11) of the filter housing (10) andseparates the lower inner chamber (16) of the filter housing (10)disposed beneath the filter matte (13) from a frontal region (20) whichcontains the air inlet (11) and the water outlet (18).
 16. The airfilter according to claim 3, wherein the water separator (19) isdisposed inclined at an acute angle to the axis of the air inlet (11) ofthe filter housing (10) and separates the lower inner chamber (16) ofthe filter housing (10) disposed beneath the filter matte (13) from afrontal region (20) which contains the air inlet (11) and the wateroutlet (18).
 17. The air filter according to claim 4, wherein the waterseparator (19) is disposed inclined at an acute angle to the axis of theair inlet (11) of the filter housing (10) and separates the lower innerchamber (16) of the filter housing (10) disposed beneath the filtermatte (13) from a frontal region (20) which contains the air inlet (11)and the water outlet (18).
 18. The air filter according to claim 5,wherein the water separator (19) is disposed inclined an acute angle tothe axis of the air inlet (11) of the filter housing (10) and separatesthe lower inner chamber (16) of the filter housing (10) disposed beneaththe filter matte (13) from a frontal region (20) which contains the airinlet (11) and the water outlet (18).
 19. The air filter according toclaim 7, wherein the water separator (19) is disposed inclined at anacute angle to the axis of the air inlet (11) of the filter housing (10)and separates the lower inner chamber (16) of the filter housing (10)disposed beneath the filter matte (13) from a frontal region (20) whichcontains the air inlet (11) and the water outlet (18).
 20. The airfilter according to claim 17, wherein the water separator (19) isembodied as a grating.